How Well Do You Know 5G?
2020-10-31 | 4 min read
5G technology is revolutionizing cellular communications, expanding its reach beyond cell phones. 5G will enable virtual and augmented reality, vehicle-to-everything (V2X) communications, the industrial internet of things (IIoT), and bring communications services to new places through satellite technology.
Enabling these applications requires significant technical advancements and a complete overhaul of the cellular network. Put simply, 5G is not your father’s 4G. The technology is drastically different from previous generations of cellular technology.
Millimeter-wave (mmWave) frequencies and wider bandwidths bring new challenges to design and test engineers. 5G operates in two frequency ranges: frequency range 1 (FR1) from 410 MHz to 7.25 GHz and frequency range 2 (FR2) from 24.25 to 52.6 GHz. A single component carrier now has up to 400 MHz of channel bandwidth and the channel properties of higher frequencies require the use of different multiple-input / multiple-output (MIMO) variants for each frequency range.
Using orthogonal frequency-division multiplexing (OFDM) modulation, each channel bandwidth has an underlying resource grid underneath. The numerology changes depending on how far apart the subcarriers are. Understanding the underlying resource grid of 5G channels and how 5G uses waveforms and modulation schemes to optimize signals for various scenarios is essential to address different applications.
You also need to understand the protocol structure for 5G as there are notable changes including a new service data adaptation protocol (SDAP) layer for quality of service (QoS) management in the user plane and a new feature enabling packet data convergence protocol (PDCP) duplication for mapping packet data units (PDUs) to more than one logical channel and sending them over different component carriers.
Also, the radio link control (RLC) and the media access control (MAC) layers now support beam management procedures and transmission modes using different numerologies and transmission time intervals. New additions to the physical channels include phase tracking reference signal (PTRS) for tracking phases and time scheduling, demodulation reference signal (DMRS) for the uplink control channel, and using the downlink broadcast channel.
The move to mmWave frequencies in 5G also brings beamforming and beam management challenges. Using more transmit/receive (Tx/Rx) antennas compensate for the high loss at these frequencies. More radiating elements enable you to steer the direction of the antenna. The beams also become narrower and more defined increasing received power to the user equipment. However, lossy cables and greater device/system integration drive testing to be mostly done over the air.
To learn the fundamentals of the 5G standard, take Keysight University’s course Understanding 5G New Radio Standards – A 5G Primer. If you are more seasoned in this space, you can prove your knowledge by acing the quiz at the end and receiving the certificate of completion.